Locking attachment for electric extension cords



V. C. BROWN May 6, 1958 2 Sheets-Sheet 1 Filed April 25 1955 INVENTOR NMNM mN Q aw \NN N t NI L kw? Q E w mm w an ATTORNEY y 6, 1953 v. c. BROWN2,833,997

LOCKING ATTACHMENT FOR ELECTRIC EXTENSION CORDS Filed April 25, 1955 2Sheets-Sheet 2 I N VENTOR r0 urn BY/z.

AORNEY United States Patent LOCKING ATTACHMENT FOR ELECTRIC EXTENSIONCORDS Vincent C. Brown, Big Stone City, S. Dak. Application April 25,1955, Serial No. 503,508

2 Claims. (Cl. 339-90) This invention relates to a novel lockingattachment of extremely simple construction which may be readily appliedto the ends of conventional electric extension cords and to an electricsocket of a conventional electric outlet to prevent disconnection of anextension cord resulting from a pull thereon.

Considerable inconvenience and annoyance occurs in connection with theuse of electric extension cords with hand tools such as electric saws,drills, vacuum cleaners and irons, due to the electric cord becomingaccidently disconnected as a result of a pull thereon.

Accordingly, it is a primary object of the present invention to providea locking attachment capable of being readily utilized with conventionalelectric extension cords and which may be quickly and easily appliedthereto or removed therefrom and when utilized will eifectively functionto prevent such accidental disconnection of the extension cord and theinconveniences resulting therefrom.

Various other objects and advantages of the invention will hereinafterbecome more fully apparent from the following description of thedrawings, illustrating a presently preferred embodiment thereof, andwherein:

Figure 1 is an elevational view, partly in cross section, takensubstantially along a plane as indicated by the line 1-1 of Figure 2,showing a part of the attachment, associated with a conventionalelectrical outlet, including portions shown broken away to illustratedetails;

Figure 2 is a longitudinal sectional view illustrating parts of theattachment for connection to a receptacle plate, taken substantiallyalong a plane as indicated by the line 22-2 of Figure 1, and on anenlarged scale;

Figure 2A is a view similar to Figure 2 showing parts of the attachmentfor connecting a plug and socket in a line cord;

Figure 3 is a cross sectional view taken substantially along a plane asindicated by the line 3-3 of Figure 2A;

Figure 4 is a fragmentary top plan view of a portion of the attachmentshown in Figure 2A;

Figure 5 is a fragmentary longitudinal sectional'view illustrating apart of the attachment;

Figure 6 is an end elevational view, partly in cross section,illustrating certain of the parts of the attachment assembled, as saidparts appear looking down on Figure 7;

Figure 7 is an enlarged vertical sectional view, taken substantiallyalong a plane as indicated by the line 7-7 of Figure 6, and

Figure 8 is a fragmentary side elevational view of the housing of onepart of the attachment as illustrated in Figures 6 and 7.

Referring more specifically to the drawings, the looking attachment inits entirety and comprising the invention is designated generally 10 andincludes locking or connecting units, designated generally 11, 12, 13and 14.

The unit 11 which is of primary utility and which may be utilized withthe units 12, 13 and 14, includes a sleevelike housing 15 of relativelylarge diameter which is preferably encircled by reinforcing rings 16which are spaced from the ends 17 and 18 thereof. The housing 15 may beformed of metal or plastic, or other suitable material and is providedwith oppositely disposed bayonet slots 19 which open outwardly of itsforward end 17. The housing 15, adjacent the end 17, is also providedwith a pair of diametrically aligned outwardly projecting connector pins20, which are circumferentially spaced from the bayonet slots 19. Therear end 18 is preferably provided with an annular internal flange orlip 21 providing a seat for a ring member 22 which is disposed in thehousing 15. The locking unit 11 also includes a conical shaped spinalexpansion spring 23 which is removably contained in the housing 15thereof.

Referring to the unit 11, as illustrated in Figure 2, it will be readilyapparent that the spring 23 can be removed through the housing end 17and that the plug 24 of a conventional electric extension cord 25 can beinserted through the housing 15, entering through the end 18 and throughthe ring 22 contained therein. The plug 24 can be displaced a suflicientdistance in advance of the forward end 17, so that the spring 23 canthen be applied to the extension cord 25, by passing a part of the cordspirally between the spring convolutions, and so that the smallest endconvolution 23a of the spring will be disposed adjacent to and can bepositioned in abutting engagement against the back of the plug 24. Theextension cord 25 can then be drawn from front to rear through thehousing 15 to cause the spring 23 to resume its position in said housingand with its largest end convolution 23b abutting against the ring 22,

It will thus be apparent that the as seen in Figure 2. unit 11 can bequickly attached to or detached from a conventional extension cord, andwithout the use of plate 26 is adapted to be disposed over aconventional electrical outlet 28, such as a domestic wall outlet and isdetachably secured thereto by screw fastenings or the like 29, whichextend through the plate, adjacent the ends thereof, and are anchored ina wall or to the outlet 28.

The plate 26 near to its ends is provided with outwardly projectingannular flanges 30 defining flanged openings through the plate 26 andwhich align with two end sockets 31 of the outlet 28. The plate 26 ispreferably provided with an intermediate opening 32 which aligns with anintermediate socket 31 of the outlet 28 and in' which any conventionalelectric plug may fit for connection to the intermediate socket 31. Eachof the annular flanges or bosses 30 is provided with a pair ofdiametrically aligned outwardly projecting connector pins 33, which arespaced from the plate 26, as seen in Figure 2.

It will be readily obvious that the plug 24 can be extended slightlyfromthe housing end 17 and can be inserted through one of theflanges orbosses 30 for inserting the prongs 24a thereof into the socket 31 whichaligns with'said boss 30. The housing 15 can then be displaced" relativeto the plug 24 toward the plate 26. The interior diameter of the housing15 is larger than the exterior diameter of the boss 30 so that the end17 thereof can be partially telescoped over the boss 30 and with thebayonet slot portions 19a, which extend longitudinally of the housing 15receiving the connector pins 33. When the pins 33 reach the inner endsof the slot portions 19a, the housing 15 can be turned relative'to theboss 30 in a conventional manner for locking the pins 33 in thecircumferentially extending bayonet slot portions 19b. The spring 23nected from the socket 31 while the unit 11 is thus locked to the unit12. The other end of the extension cord 25 is illustrated in Figure 22%:as being provided with a conventional single socket 34. However, it willbe readily apparent that said last mentioned end of the extension cord25 could be directly connected to a power tool, vacuum cleaner, iron orthe like, in which case only the units 11' and 12 would be required forlocking the extension cord 25 so that the electrical connection providedthereby could not be inadvertently broken.

However, Figure 2A shows a second identical unit 11 in which theextension cord socket 34 is disposed and which is assembled relative tothe extension cord socket 34, in the same manner as the unit 11,previously described, is assembled with the extension cord plug 24.The'unit 13, as illustrated in Figure 2A, includes a sleevelikehousing'3'5 the external diameter of which is slightly smaller than theinternal diameter of the housing 15. The housing 35 has a forward end36, adjacent to which the" housing is provided with diametricallyaligned outwardly projecting connector pins 37. However, the housing 35is not provided with bayonet slots. The other rear end 38 of the housing35 has an internal lip 39 for seating a stop ring 40, corresponding tothe lip 21 and ring 22, respectively, except as to the size of saidparts. The connector unit 13 also includes a conical spring 41,corresponding to the spring 23, except as to its diameter, and which ismounted in the same manner and functions for the same purpose. A plug 42of an extension cord 43 is mounted in the unit 13, in the same mannerthat the plug 24 is mounted in the left hand unit 11. It may be assumedthat the opposite end of the extension cord 43 is connected to anelectrical tool, vacuum cleaner, iron or the like. For connecting theextension cords 25 and 43, the socket 34 and the plug 42 are permittedto be extended by their springs 23 and 41, respectively, from theforward endsof the housings 15 and 35 thereof, so that the prongs 42a ofthe plug 42 can be engaged in the socket 34 for completing an electricalconnection from the wall outlet socket 31 to the extension cord 43. Theunit 11 individual to the socket 34 and the unit 13 can then bedisplaced towardone another for causing the housing end 36 to enter thehousing. end 17 and for causing the connector pins 37 to enter thebayonet slot portions 19a, after which a turning movement of one of thehousings relative. to the other in the correct direction will elfect alocking of the connector pins 37 in the slot portions 1%, as seen inFigure 4 for thus locking the units 11 and 13 together and so'that theplug 42 will be re tained in engagementwith the socket 34by the twocompressed springs 23' and 41' which bear against the plug24 and socket42, respectively, to thus prevent accidental disengagement of thiselectrical connection. Thus, it will-be apparent that the end 17 of theunit 11 is adapted for attachment in the same manner to either a boss 30or the end' 47. The forward'end-46 is provided with'bayonet slots 48,-corresponding to the bayonet slots 19. The

housing portion 45 nea'r'itsrear end-47 ispro'vided with pins or studs49 which project inwardlytherefroin andwhich are circutnferentially'spaced relative to one another. The housing portion 45 is preferablyprovided with an internal groove 50 disposed inwardly ofand adjacent theprojections 49. The housing portion 45,

spaced from the ends thereof, is provided with aligned annular flangeportions 51 which project outwardly therefromand which surroundopenings- 52 of the part 45,

which are disposed in" alignment with one another and which aresubstantially smaller-in diameter than the in ternal diameter of theflang'e's' oi bosses-51. The external .4 diameter 'of the bosses 51correspond to the external diameters" of the bosses" 30 and housing 35and, like said parts, are each provided with a pair of outwardlyprojecting aligned connector pins 53. The unit 14 also includes aconical spring 54, similar to but somewhat larger than the spring 23.

Anend of an extension cord 55 of a conventional construction is shownprovided with a conventional threeway socket 56 two socket portions 57of which are disposed in transverse alignment and the other socketportion 58 of which is disposed longitudinally of the body of thethree-way socket 56. It will be readily apparent that the end of theextension cord 55 illustrated in Figure 7 could constitute the righthand end of the extension cord 25 of Figure 2A, with the three-waysocket 56 substituted for the single socket 34. Said three-Way socket 56is inserted through the rear end 47 of the housing part 45, between theprojections 49, and is passed outwardly through the forward end 46,after which the spring 54 is applied to the cord 55 with its smallestend positioned against the end of the socket 56 from which the cord 55projects. The spring and socket are then drawn back into the housingportion 45 through its forward end 46 and the largest outer convolutionof the spring 54 is adapted to seat in the groove 50 and against theprojections 49.

A unit 11, identical with the unit 11 of- Figure 2 and containing'a plug24, is adapted to have its forward end 17 telescoped' into the forwardhousing end 46 andlocked' thereto, by its connector pins 20 engaging inthe'bayonet slots 48, in the manner as previously described inreferencetothe other bayonet connections. The unit 11 shown at the top of Figure7 is thus locked to the housing end 46, after the plug 24 thereof hasbeen engaged with the socket'portion 58, and so that the connectedsocketportion 58 and plug 24 will be held between the spring 54 and theupper spring 23 of Figure 7, both of which will be under tension toretain the socket portion 57 properly positioned lengthwise of thehousing part 45 for alignment with the openings 52.

Another'unit 11-, corresponding to theunit shown at the top of Figure 7and having a plug 24 canthenbe attached to one of the socket portions57, by inserting the plug 24* thereof inwardly through the boss 51,individual to said-socket-portion 57', and so that the plug prongs 24awill pass inwardly through the connecting openings 52 to'engage in theso'cket57; The housing 15 ofsaid last mentioned until 11 can then beengaged and locked to the boss 51,-irlth'e same-manner mat the unit 11is engaged and ldckedwith the boss 30, as seen in Figure 2. It will alsobe-obvious that a third corresponding unit 11 can beco'nnected to theother boss 51, for thus locking three ing said adjacent sleeve endstogether, expansion spiralspriiigs ofconical shapedisposed insaid-sleeves and through-which electric cords are adapted to extendfrornremote ends of the plug and socket outwardly throughremote ends ofsaidsleeves, said springs having restricted adjacent ends bearing againstthe plug and socket and enlarged remote ends, said sleeves havinginternal restrictiohsat the remote ends thereof forming seats for theenlarged ends of said springs for maintaining the springsu'nder tensionbetween'the spring seats and the coupled plug and socket when saidsleeves are connected in interfitting relation to one another and forurging the plug and socket to projected and exposed positions outwardlyof said adjacent ends of the sleeves when said sleeve ends aredisconnected.

2. A locking attachment as in claim 1, said second sleeve having atleast one laterally extending tubular branch opening internally thereof,said socket having a lateral socket portion held in alignment with saidbranch by said springs when the sleeves are interlocked together, athird sleeve containing a second plug receivable into said branch forelectrical connection to said laterally opening socket portion, meansinterlocking said third sleeve in telescopic engagement with saidtubular branch, and a spiral spring seated in an outer end of said thirdsleeve and beating against the second plug for urging said second pluginto the tubular branch and for retaining second plug in engagement withthe laterally opening socket portion.

References Cited in the file of this patent UNITED STATES PATENTS1,304,075 Lofgren May 20, 1919 2,005,475 Schmidt June 18, 1935 2,015,953McDowell Oct. 1, 1935 2,066,770 Doane Jan. 5, 1937 2,129,914 Davis Sept.13, 1938 2,398,626 Del Camp Apr. 16, 1946 2,409,732 Brown et a1. Oct.22, 1946 2,447,783 Williams Aug. 24, 1948 2,690,542 Pearce Sept. 28,1954

